Sinn Fein is trying to exploit the UK's impending exit from the EU and alienate unionists for its own electoral advantage, Fianna Fail leader Micheal Martin has claimed.

The Opposition leader has hit out at Gerry Adams for proposing a new Oireachtas committee that would begin planning for a united Ireland.

Mr Adams recently wrote to all party leaders in Leinster House seeking support for the proposal but was shot down by Fianna Fail.

The Sinn Fein President yesterday called on Mr Martin to "get serious" about Irish unity.

However, Mr Martin said the establishment of the committee proposed by Sinn Fein would "send all the wrong signals to unionists".

"I think if unionists see all of the parties in the Republic coming together minus them, it creates a certain impression. They would feel under threat immediately," he commented.

Fianna Fail is compiling its own proposals for how a united Ireland might operate.

It is expected to be ready for publication later this year.

Mr Martin said the full potential of the Good Friday Agreement has not yet been delivered and Sinn Fein should be focusing on this.

"My own sense is that Sinn Fein is exploiting the Brexit situation to try to create a new platform for his own electoral advantage.

"They are doing damage to the prospect of unity by consent," he accused.

Mr Martin added that the full focus of political parties should be on restoring devolved government in Northern Ireland.

Mr Adams however said the committee proposed by Sinn Fein would provide a forum where party interests could be left at the door.

"The recent experience of the chaos in Britain, caused by the vote to leave the EU, shows that possibilities of large scale change need to be planned for in advance.

"Crucially, part of the work of the committee would be to put in place a vision for the future of the island that assures unionists of their place in a New Ireland.

"This has to be an agreed Ireland. It will not happen by accident," he said.

Meanwhile, Sinn Fein Brexit spokesperson John O'Dowd has issued a fresh challenge to the Dublin government.

The Upper Bann MLA was commenting as the second round of formal Brexit talks between UK Government representatives and EU officials got underway in Brussels.

He said Dublin had to make its top priority "designated special status for the North to remain in the EU".

"That is the only way to avoid a new frontier on the island of Ireland, given that the EU has already warned that border checks are inevitable in the event of Britain leaving the Customs Union," he added.